This invention relates to a high frequency surgical snare electrode, particularly for endoscopes having an instrument channel for slidably displaceably receiving the electrode, a flexible guide channel insulated at least on the outside, a flexible electrode lead slidably displaceable in the guide channel, and a resilient snare electrode attached to the free end of the electrode lead next to the patient and being capable of resiliently spreading apart when moved out of the guide channel and of being completely or nearly completely retracted into the guide channel by the electrode lead.
High frequency surgical snare electrodes of the foregoing type are known from the German published patent specification (Auslegeschrift) No. 21 32 808 or the German published patent application (Offenlegungsschrift) No. 29 41 060. The snare electrode is used in the removal of growths, such as stomach and intestinal polyps, for example, whereby the growth formations are excised by electrotomy, implemented by retracting the snare electrode connected by the electrode lead to a source of power.
The known snare electrode is provided at its end opposite the electrode lead with a semi-circularly curved section, the diameter of which is smaller than a guide bushing positioned at the confronting end of the guide channel, and smaller than the inner diameter of the guide channel. The semi-circular curvature is intended to ensure that the elasticity limit of the snare wire is not exceeded when the snare electrode is completely retracted.
The diameter of the wire of the snare electrode is very small in order to keep the diameter of the guide channel as small as possible. The known snare electrodes are exposed to strong thermal forces exerted by the cutting current on the area of the curved section and tend to burn through at a point along the curvature already after short use.